1. Field
The present disclosure relates to a glass composition for sealing a large-area dye-sensitized solar cell, and more particularly, to a composition for manufacturing a glass material which may be uniformly bonded to a large-area without reacting with an electrolyte.
2. Description of the Related Art
Dye-sensitized solar cells said to be a next-generation solar cell is a future-oriented solar cell used for generating and absorbing electrons by using a glass dye and allowing a long-term service. Recently, as the development of an alternative energy source is accelerated due to the depletion of energy sources, the dye-sensitized solar cells are being actively developed.
Dye-sensitized solar cells use a transparent glass substrate and can freely display various colors according to the type of dye, and can be conveniently fabricated in various sizes, so they are expected to be easily used over a wide range of applications, and are of high use. However, because efficiency is still low at the current level of development, they are not fully used in all possible applications and applied products, and large-area dye-sensitized solar cells are produced on a trial basis and some are being used for interior applications on windows or walls of buildings. Accordingly, the potential for development of dye-sensitized solar cells is high, and in this instance, large-area fabrication and stabilized efficiency of dye-sensitized solar cells are important factors of development.
In addition to a dye, dye-sensitized solar cells use an electrolyte as an electron transport channel, and liquid electrolytes differ in components according to the type of dye. In order to use a liquid electrolyte, a partition wall is needed to prevent an electrolyte from leaking, and Surlyn Film™ of DuPont which is a polymer material is used as a sealing material for a conventional dye-sensitized solar cell. However, Surlyn film has limitations in perfect blocking in the respect that it has low mechanical durability, is difficult to achieve precise bonding because it is of film type, and is prone to react with oxygen or water due to the properties of organics to give possibility of transmission of gas or moisture. Further, for large-area fabrication, precise bonding and high mechanical durability for maintaining adhesion of a large-area substrate are required, but Surlyn film is difficult to satisfy these requirements.
To solve the problem, glass is used as a sealing material to ensure the mechanical durability and allow uniform bonding by a screen printing method using a paste with glass powders, namely frit. Furthermore, formulation capable of minimizing reactivity of glass with an electrolyte is required in order to ensure the chemical durability.
On the other hand, TiO2 is used as an electron transport material of a dye-sensitized solar cell, but TiO2 changes in crystal structure depending on the phase, and in this instance, in the case of phase having the greatest electron transport ability, a phase transition occurs at 550° C. or above, and accordingly, there is a need for glass formulation that can be fired at lower than 550° C.
There are results of studies using, as a sealing material, commercial glasses conventionally used, such as boro-silicate or soda-lime, but high process temperature is required, and thus, bonding is not easy. Furthermore, there are instances of using a laser for sealing to replace high process temperature, but precise laser control is difficult, so difficulty in uniform bonding still exists. Moreover, commercial glass formulations have high reactivity with an electrolyte, and are thus released and precipitated, insufficient for sealing.
Many studies have been made to solve the above problems, and glasses with excellent chemical stabilization to an electrolyte have been developed. However, large-sized bonding is difficult due to low adhesive force, and there is also a problem in long-term durability.